Mobile terminal

ABSTRACT

There is provided a cellular phone taking into consideration enhancement in processing speed and reduction in current consumption, and the cellular phone comprises a processing unit capable of executing plural kinds of processing, an oscillator for generating a clock signal to be fed to the processing unit, and a clock controller for converting the frequency of the clock signal received from the oscillator, wherein the clock controller changes the frequency of the clock signal for each of the plural kinds of the processing in response to the control by the central processing unit.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a cellular phone comprising acentral processing unit (CPU).

[0002] A hand-held terminal or mobile terminal, for switching thefrequency of a clock signal delivered from the side of an applicationprogram, is disclosed in JP-A NO. 73237/1999 (Heisei 11).

[0003] Further, in JP-A No. 148475/2000, there is disclosed a computerfor a mobile unit, capable of switching a clock frequency to ahigh-speed mode frequency higher than a normal frequency whenconditions, such as power source voltage, ambient temperature, and soforth, are satisfied.

[0004] In the case of the conventional technology described above, speedcontrol of a clock signal has been implemented by an application programor has been dependent on the conditions such as power source voltage,ambient temperature, and so forth, so that there is no room forinterposition of the will of a user in switching the speed of the clocksignal. Further, if the CPU is driven at a high frequency, there hasbeen a tendency toward an increase in current consumption although aprocessing speed is enhanced. With a cellular phone, in particular,since its battery capacity is small, there has been a risk of prematuredepletion of the battery capacity occurring when the clock signal hasbeen automatically switched over to the high-speed side withoutknowledge of the user.

SUMMARY OF THE INVENTION

[0005] To attain both enhancement in processing speed and reduction incurrent consumption, it is an object of the invention to provide amobile terminal comprising clock control means capable of changing thefrequency of a clock signal received from an oscillator under control bya central processing unit, and converting an operation frequency of thecentral processing unit to a different frequency, wherein a clock signalat the different frequency as converted by the clock control meansbecomes a clock signal of the central processing unit.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]FIG. 1 is a block diagram showing the configuration of a firstembodiment of a cellular phone according to the invention;

[0007]FIG. 2 is a block diagram showing the configuration of a secondembodiment of a cellular phone according to the invention;

[0008]FIG. 3 is a block diagram showing the configuration of a thirdembodiment of a cellular phone according to the invention;

[0009]FIG. 4 is a block diagram showing the configuration of a fourthembodiment of a cellular phone according to the invention; and

[0010]FIG. 5 is a graph showing the relationship between an operationfrequency of a central processing unit of the cellular phone accordingto the first to fourth embodiments, respectively, and currentconsumption.

[0011] Other and further objects, features and advantages of theinvention will appear more fully from the following description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A first embodiment of a cellular phone according to the inventionis described hereinafter with reference to FIGS. 1 and 5. FIG. 1 is ablock diagram showing the internal configuration of the cellular phoneaccording to the first embodiment.

[0013] A central processing unit (CPU) 100 controls the operation of thecellular phone in accordance with a control program stored in a memory110. The CPU 100 performs operation in accordance with an inputpushbutton as pressed via an operation panel (input pushbutton group)120, executing processing in response to the input pushbutton aspressed.

[0014] Upon dialing, a telephone number as inputted from the operationpanel 120 is shown on a display unit 130, a speech signal delivered froma speech input unit (microphone) 140 is sent out in the form of radiowaves from an antenna 160 to the outside via a transmit/receive unit 150in accordance with a transmission directive delivered from the operationpanel 120.

[0015] At the time of signal reception, radio waves from the outside arereceived by the antenna 160, and upon recognition by thetransmit/receive unit 150 that the radio waves received are radio wavescorresponding to a telephone number dedicated to the present cellularphone, speech is delivered from a speech output unit (speaker) 170.

[0016] The CPU 100 receives a clock signal from an oscillator 180through the intermediary of a clock controller 200. Because an operationfrequency of the CPU 100 is dependent on the frequency of the clocksignal as received, a processing speed of the CPU 100 is regulated bythe frequency of the clock signal. The clock controller 200 converts thefrequency of the clock signal into any suitable frequency by use of aPLL (Phase Locked Loop) circuit under control by the CPU 100, and theclock signal is delivered to the CPU 100 as a clock signal of the CPU100. The frequency of the clock signal delivered to the CPU 100 becomesthe operation frequency of the CPU 100.

[0017]FIG. 5 is a graph showing the relationship between the operationfrequency and current consumption. In proportion as the frequency of theclock signal is changed to a higher frequency, the operation frequencyof the CPU 100 becomes higher, thereby enhancing the processing speed ofthe CPU 100 although current consumption increases.

[0018] With the present embodiment, when executing a specificprocessing, the frequency of the clock signal of the CPU 100 is causedto change to a higher frequency, thereby enhancing the processing speed.Upon completion of the execution of the specific processing, thefrequency of the clock signal of the CPU 100 is caused to change to alower frequency, thereby reducing current consumption. In the initialcondition at the time when power is turned on, the frequency of theclock signal of the CPU 100 is set to a low frequency in order to reducecurrent consumption.

[0019] Herein, the specific processing refers to, for example,processing for image decoding, address retrieval processing, andapplication processing such as kana-kanji conversion processing used inentering characters. These processing often have effects on the responseof the user.

[0020] With the present embodiment, the user can change the operationfrequency of the CPU 100 by changing the output frequency of the clockcontroller 200 at will with the use of a clock manipulation unit 300connected with the CPU 100.

[0021] If the user enters a request for change via the clockmanipulation unit 300, the CPU 100 receives an input from the clockmanipulation unit 300, and controls the clock controller 200, therebycontrolling a clock frequency to be fed to the CPU 100. That is, inresponse to the input from the clock manipulation unit 300, thefrequency of the clock signal to be fed to the CPU 100 is set.

[0022] Further, with the present embodiment, depending on an applicationto be used, and use environments, the user can change the frequency ofthe clock signal in every processing. For example, if the user wants toincrease the processing speed of the CPU 100, the frequency of the clocksignal can be raised, and if the user wants to reduce currentconsumption, the frequency of the clock signal can be changed to a lowerfrequency. By virtue of such a function as described, the user can setthe frequency of the clock signal as appropriate at will depending onthe user's use environments, such as the user desire to execute highspeed processing, or to use the cellular phone for many hours, theamount of the actual battery capacity that remains in a battery beingsmall, and so forth, so that operability can be enhanced.

[0023] In FIG. 1, the clock manipulation unit 300 is shown as a singlepushbutton (clock manipulation pushbutton), but may be made up of aplurality of keys instead. In order to implement the clock manipulationunit 300 with the single pushbutton, for example, the lowest frequencyis set as the initial condition of the frequency of the clock signal,thereby carrying out control such that every time when the singlepushbutton is once operated, the frequency of the clock signal of theCPU 100 is changed to sequentially higher frequencies by stages. Thefrequency is changed cyclically, and if the frequency of the clocksignal of the CPU 100 is changed to the highest frequency, uponoperation of the single pushbutton the next time, the frequency of theclock signal of the CPU 100 reverts to the lowest frequency. Thus, everytime when the single pushbutton is operated, the output frequency of theclock controller 200 can be changed, thereby enabling the operationfrequency of the CPU 100 to be changed.

[0024] The CPU 100 causes the display unit 130 to display a numericalvalue of the frequency after changed in such a way as to explicitlyadvise the user of the frequency of the clock signal after changed.Since it is sufficient for such display to indicate simply which stagethe processing speed of the CPU 100 is in, indication of a specificnumerical value of the frequency is not necessarily required. Numbers toindicate respective stages, such as 1, 2 , 3 . . . , or characters suchas high, middle, low, etc. may be displayed. Alternatively, therespective stages of the processing speed may be displayed in number ofstars, exhibiting one star on the display unit 130 for the lowest speed,increasing the number of stars exhibited on the display unit 130 inascending order of the stage. Otherwise, the status of the processingspeed may be displayed with the use of a bar graph, icons, and so forth.

[0025] Further, for changing the output frequency of the clockcontroller 200 at the user's will, there may be adopted a method wherebyan operation menu directing change of the frequency of the clock signalis caused to be displayed on the display unit 130 without the use of theclock manipulation pushbutton, and the user selects or directs at willthe output frequency of the clock controller 200 by use of the operationpanel 120, thereby changing the operation frequency of the CPU 100. Insuch a case, the operation panel 120 functions as the clock manipulationunit 300, so that the clock manipulation unit 300 can be omitted.

[0026] Now, a second embodiment of a cellular phone according to theinvention is described hereinafter with reference to FIG. 2. FIG. 2 is ablock diagram showing the internal configuration of the cellular phoneaccording to the second embodiment.

[0027] With the present embodiment, a central processing unit (CPU) ismade up so as to be divided into a first central processing unit 400concerned with transmit/receive of signals, and a second centralprocessing unit 410 handling processing that has effects on the responseof a user. In FIG. 2, blocks denoted by the same reference numerals asthose in FIG. 1 correspond to those blocks of the first embodiment,having the same functions.

[0028] The first central processing unit 400 controls operationconcerned with transmit/receive by the cellular phone in accordance witha control program stored in a first memory 420, and the second centralprocessing unit 410 controls operation concerned with processing thathas effects on the response of a user in accordance with a controlprogram stored in a second memory 430. More specifically, the secondcentral processing unit 410 controls operation concerned with processingof an application program.

[0029] A clock signal from an oscillator 180 is directly delivered tothe first central processing unit 400 as a clock signal. Meanwhile, aclock signal at any suitable frequency converted by control of thesecond central processing unit 410 is delivered to the second centralprocessing unit 410 through the intermediary of a clock controller 200.

[0030] With such a configuration as described, when executing a specificprocessing, the frequency of the clock signal delivered to the secondcentral processing unit 410 can be changed to a high frequency, therebyenhancing a processing speed, and upon completion of execution of theprocessing that has effects on the response of the user, the frequencyof the clock signal delivered to the second central processing unit 410can be changed to a low frequency, thereby reducing current consumption.

[0031] For example, during a standby (waiting) period for communicationsby the cellular phone, the first central processing unit 400 is inintermittent operation to receive radio waves from the outside via anantenna 160, executing processing for recognition by thetransmit/receive unit 150 that the radio waves received are radio wavescorresponding to a telephone number dedicated to the present cellularphone. In this case, the frequency of the clock signal delivered to thesecond central processing unit 410 is changed to a low frequency tothereby reduce current consumption. As shown FIG. 5, the relationshipbetween an operation frequency and current consumption is such that inproportion as the operation frequency becomes higher, the currentconsumption increases while in proportion as the operation frequencybecomes lower, the current consumption decreases.

[0032] The cellular phone shown in FIG. 2 further comprises a powersupply controller 500. The power supply controller 500 controls power tobe supplied from a battery 510 to the second central processing unit 410in response to control by the first central processing unit 400. Forexample, during a standby (waiting) period for communications by thecellular phone or upon completion of the processing by the secondcentral processing unit 410, the power supply controller 500 can turnoff power to be supplied to the second central processing unit 410 inresponse to control by the first central processing unit 400. Since thesecond central processing unit 410 handles application, its powerconsumption at the time of processing is large, and consequently,effective saving in power can be attained by controlling the powersupplied.

[0033] Next, a third embodiment of a cellular phone according to theinvention is described hereinafter with reference to FIG. 3.

[0034] The cellular phone shown in FIG. 3 comprises a battery voltagedetector 600 in place of the power supply controller 500 incorporated inthe cellular phone shown in FIG. 2. In FIG. 3, blocks denoted by thesame reference numerals as those in FIG. 2 have the same functions asthose of the blocks of the second embodiment, omitting thereforedescription thereof.

[0035] The battery voltage detector 600 detects a voltage of a battery510. A first central processing unit 400 determines whether or not thevoltage detected is lower than a predetermined value. In the case whereit is determined that the amount of the actual battery capacity thatremains in the battery 510 is less than a predetermined amount, thefrequency of a clock signal delivered to a second central processingunit 410 is changed to a lower frequency even when executing a specificprocessing, thereby reducing current consumption. Hence, it is possibleto effect control so as to reduce current consumption in case that theamount of the actual battery capacity that remains in the batterybecomes small, thereby prolonging operable time of the cellular phone.

[0036] Further, a fourth embodiment of a cellular phone according to theinvention is described hereinafter with reference to FIG. 4. FIG. 4 is ablock diagram showing the internal configuration of the cellular phoneof a folded structure, according to the fourth embodiment. In FIG. 4,blocks denoted by the same reference numerals as those in FIGS. 2 and 3,respectively, have the same functions as those of the blocks of thesecond and third embodiments, respectively, omitting thereforedescription thereof.

[0037] The cellular phone shown in FIG. 4 comprises a folding conditiondetector 700 for detecting whether the cellular phone is in a folded(closed) condition or in an unfolded (open) condition.

[0038] With the cellular phone according to the present embodiment, afirst display unit 710 and a second display unit 720 are added to afirst central processing unit 400 and a second central processing unit410, respectively. The first display unit 710 is disposed at a positionas can be seen by a user even in the folded condition. The seconddisplay unit 720 is disposed at the folded-down side of the cellularphone.

[0039] Since the operation of the cellular phone in the open conditionis the same as that of the cellular phone according to the second andthird embodiments, respectively, the operation of the cellular phone inthe closed condition is described hereinafter.

[0040] Normally, in the closed condition, the cellular phone is often onstandby (waiting) for cellular phone communications, and the firstcentral processing unit 400 is in intermittent operation to receiveradio waves from the outside via an antenna 160, executing processingfor recognition through the intermediary of a transmit/receive unit 150that the radio waves received are radio waves corresponding to atelephone number dedicated to the present cellular phone. Meanwhile,since a load on the second central processing unit 410 is light at thispoint in time, the frequency of a clock signal delivered to the secondcentral processing unit 410 can be changed to a low frequency, therebyreducing power consumption. When executing a specific processing even inthe closed condition, the frequency of the clock signal delivered to thesecond central processing unit 410 is caused to change to a higherfrequency, thereby enhancing a processing speed, and upon completion ofexecution of the specific processing, the frequency of the clock signalis caused to change to a low frequency, thereby reducing currentconsumption.

[0041] Further, in the closed condition, the user is unable to see thesecond display unit 720. Accordingly, as for processing concerning thesecond display unit 720, upon detection of the closed condition, thefrequency of the clock signal delivered to the second central processingunit 410 is caused to change to a low frequency, thereby enablingcurrent consumption to be reduced.

[0042] Furthermore, even when executing the specific processing, thefrequency of the clock signal delivered to the second central processingunit 410 may be changed to a low frequency in the case of the closedcondition. In the case of the cellular phone being in the closedcondition, the user does not look at a display screen of the cellularphone, and is often in no hurry to do processing. Accordingly, in thecase of the closed condition, processing can be executed while reducingpower consumption by changing the frequency of the clock signal to alower frequency. When the cellular phone is shifted to the opencondition, the processing speed is enhanced by changing the frequency ofthe clock signal delivered to the second central processing unit 410 toa higher frequency.

[0043] The cellular phone shown in FIG. 4 further comprises a lightingcontroller 800 for controlling backlight of the second display unit 720.Since the user is unable to see the second display unit 720 in thefolded condition, further reduction in power consumption can be attainedby turning off the backlight of the second display unit 720.

[0044] In addition, the power supply controller 500 shown in FIG. 2 orthe battery voltage detector 600 shown in FIG. 3 may be added to thecellular phone according to the present embodiment. In such a case, whenthe amount of the actual battery capacity that remains in the battery510 is less than a predetermined amount, power consumption can bereduced and waiting time can be extended by implementing control suchthat the backlight of the second display 720 is turned off even in theopen condition.

[0045] Still further, the operability of the cellular phone can beimproved by providing the cellular phone shown in FIGS. 2 through 4,respectively, with the clock manipulation unit 300 shown FIG. 1, therebyenabling the user to change the frequency of the clock signal as withthe case of the first embodiment. Also, the operation panel 120 may havethe function of the clock manipulation unit 300.

[0046] The respective embodiments described hereinbefore may be carriedout singly or in combination as appropriate.

[0047] With the embodiments described hereinbefore, the clockcontroller, the memories, and so forth are disposed outside of thecentral processing unit, however, these components together with thecentral processing unit may be integrated so as to be incorporated inone chip.

[0048] As described in the foregoing, with the embodiments of theinvention, it is possible to attain both enhancement in the processingspeed and reduction in the power consumption.

[0049] The foregoing invention has been described in terms of preferredembodiments. However, those skilled, in the art will recognize that manyvariations of such embodiments exist. Such variations are intended to bewithin the scope of the present invention and the appended claims.

What is claimed is:
 1. A mobile terminal comprising: an antenna whichtransmits and receives radio waves; a transmit/receive unit connectedwith the antenna; an audio signal input unit which receives audiosignals; an audio signal output unit which delivers audio signals; acentral processing unit capable of executing plural kinds of processing;a display unit which displays under control by the central processingunit; an oscillator which generates a clock signal to be fed to thecentral processing unit; and a clock controller which converts thefrequency of the clock signal received from the oscillator, wherein theclock controller changes the frequency of the clock signal for each ofthe plural kinds of the processing in response to the control by thecentral processing unit.
 2. A mobile terminal according to claim 1,further comprising a directive input unit which enters a directive froma user, wherein when the user enters a request for change in processingspeed or change in frequency from the directive input unit, the centralprocessing unit controls the clock controller so as to change thefrequency of the clock signal.
 3. A mobile terminal according to claim1, wherein when the frequency of the clock signal is changed by theclock controller, the central processing unit controls the display unitso as to exhibit a display concerning the change.
 4. A mobile terminalaccording to claim 3, wherein the display unit exhibits a displaycorresponding to the magnitude of the frequency of the clock signal byuse of a graphics or an image.
 5. A mobile terminal according to claim1, further comprising a memory that stores information concerning thefrequency of the clock signal corresponding to each of the plural kindsof the processing, and the central processing unit controls the clockcontroller in response to the information stored in the memory.
 6. Amobile terminal according to claim 1, wherein the central processingunit controls the clock controller in such a way as to lower thefrequency of the clock signal when the amount of the battery capacitythat remains in a battery becomes small.
 7. A mobile terminal accordingto claim 1, further comprising a memory that stores a control program,wherein the central processing unit execute processing in accordancewith the control program stored in the memory.
 8. A mobile terminalcomprising: an antenna for transmitting and receiving radio waves; atransmit/receive unit connected with the antenna; a first processingunit for controlling transmit/receive of signals by the transmit/receiveunit; a second processing unit for executing processing of a pluralityof application programs; an oscillator for generating a clock signal tobe fed to the first processing unit and the second processing unit,respectively; and a clock controller for converting the frequency of theclock signal received from the oscillator, wherein the clock controllercan change the frequency of the clock signal to be fed to the secondprocessing unit for each of the plurality of the application programs.9. A mobile terminal according to claim 8, further comprising adirective input unit for entering a directive from a user, wherein whenthe user enters a request for change in processing speed or change infrequency from the directive input unit, the central processing unitchanges the frequency of the clock signal to be fed to the secondprocessing unit.
 10. A mobile terminal according to claim 8, wherein theclock controller controls the frequency of the clock signal so as tobecome lower when the amount of the battery capacity that remains in abattery becomes small.